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Valid point. There are however several good reasons to to be hopeful for an averaged winter -AO. I am most interested about December, but you have to love seeing the atmosphere cooperate with the early season cold delivery, Seems if we maintain no negative surprises we roll into December and then hopefully rock and roll near the holidays, none of that post 12/20 warm up crap this year please.

An upper air feature, low pressure disturbance, that move out of far W/NW Canada going SE ( quickly ) and passes over the province of Manitoba, Canada. These features can at times drop far enough to our South and Southeast to spawn cyclogenesis. If they drop far enough to our South and the pattern is conducive they can develop into powerful East Coast snowstorms. Sometimes these storms can even stall or loop as they move NE along the Eastern Seaboard dropping feet of snow. This diving system out of Canada shares common characteristics with Alberta clippers and even Saskatchewan Screamers. The name given simply implies the location they pass over. Great link https://www.9and10news.com/2011/01/03/alberta-clipper-saskatchewan-screamer-manitoba-mauler/

So, then for me after looking at this beautiful meteorological artwork is, what about the eventual flip, and do we go back to a favorable pattern at some point ? I think any relax is minimal, but has to happen. The ensemble mean, as Maue points out, is remarkable. Lets not forget in the process of all this cold is the building snow cover extent and depth to our North and Northwest. I did read one thing from HM about N Pac ridging. However, I assume if that were a huge concern for December in the East Anthony would talk about it more. Here is the snippet from HM I was referring to: << . Too much ridging in the N PAC and you end up with a 1990 situation--big +AO next month. >>

Here is that time period John was mentioning in his post earlier today. I would say you have to consider this as a potential snow event window as well, even though it is way out there. Of course this potential event may favor regions North of us, but plenty of time to work that out. One thing of note, the continuous anomalous cold air from NW Canada feeding down the next 10 to 14 days. On a side note, I have heard from several respected mets that this winter will feature a few robust clippers and even Manitoba Maulers. I would love an exploding clipper to bomb out off the Va Capes and then doing a loop off Ocean City, MD for say 24 hours. As John stated : " Another threat for winter weather could evolve in the Northeast states from 11/11 - 11/13. As the closed ridge near the Chukchi Sea collapses, increased momentum/amplification could occur. The evolving waveguide could support a storm threat a few days later."

Cool animation John created here. Certainly seems there is potential in this time period.

@poolz1 This is a cool post I brought over from @Typhoon Tip in the NE Forum Someone asked about whether there would be a warming event by the end of November , here is what Tip wrote. To me the image and the time issue involved is very interesting. And, as Tip mentioned, in this upcoming winter we may not even need a warming to get a - AO. Sounds good to me . Here is the post <<<< If there is one, keep in mind that there is a coherent time-lag in the statistical correlation. Any subsequent forcing on the Arctic Oscillation lags by as much as 20 to 30 days. Few know this, or, demonstrate very readily via turns of phrase and deliveries of prose where they've beautifully ( otherwise ) fused the sudden stratospheric warming sciences into their speculative, and I'm like " ...you do realize the effects of SSW are outside your forecast range, right?." There is a particularity that needs to be observed, else ... whatever is being observed is more likely to fail coherent forcing on the AO outside of coincident index numerology. The warm plume has to propagate downward in time ( i.e., 'downwelling' ). In every case of SSW graphical layout back to 1979, this downward motion appears to 'spiral' away from a central axial point that begins near the axis of PV rotation, at a very high beginning SIGMA level - typically between 5 and 30 hPa. As it descends, it will first appear to weaken, before the next node comes in warmer, then fades slightly ... then warmer, each node gaining x-coordinate distance upon each emergence. That growth in the x-coordinate is a representation of gaining distance from the axis of rotation. Notice the ending node is almost faded/indistinquishable in anomaly relative to the surrounding features of the ambient field ( nearing 150 hPa SIGMA) there bottom right along the nodal curve. That is tropopausal mechanical absorption/ increasing stabilization and suppression of the depths ensues, and that weakens the PV ... "pancaking" and blocking in the mid and upper troposphere ignites. This entire translation of events, as you can see took ~ from Jan 15th to the end of February ... and we can see in this case a very clear and coherent AO correlation taking place: 2013 -0.610 -1.007 -3.185 0.322 0.494 0.549 -0.011 0.154 -0.461 0.263 2.029 1.475 ... Bold is March. SSW don't really value-add like the popular mantra of the day has it in their mind(s) and bandy about. If one did take place in the last week of this month... We may be hearing about an AO response some time after Christmas.. which is fine. But, I also offer that this particular year we may not have much trouble with AO being negative anyway, so it could be lost in the din of a -AO complexion hemisphere anyway. >>>>>>>

A bit limited in time, however, I recommend this article, as it talks about various pieces of the puzzle. Here is a small section of the article . ( The article has decent images as well ) The stratospheric polar vortex shows quite a bit of day-to-day variability. This variability is caused by weather systems or large-scale waves that move upward from the troposphere into the stratosphere. In the left image (9 January 2010), we see some undulations along the edge of the polar vortex, but the vortex is generally centered on the North Pole. Two weeks later (center image on 23 January 2010) we see the center of the polar vortex pushed away from the North Pole. On a constant latitude circle, PV values are high in the eastern hemisphere and low in the western hemisphere. This is referred to as a wave-1 pattern (a wave-2 pattern can be seen in the vortex breakup section below). The wave-1 pattern develops in the troposphere and moves upward (propagates) into the stratosphere. These stratospheric waves are forced by the large-scale mountain systems and the land-sea contrasts between the continents and oceans. During the northern winter, these waves are continuously forming and moving upward into the stratosphere. The waves can “break”, much like the waves on a beach. These wave-breaking events erode the vortex and keep the polar region warmer and ozone amounts higher. Often, parts of the polar vortex are pulled away from the main vortex. The image on the right (28 January 2010) shows this, where a large piece of the polar vortex was pulled away from the main vortex (green colored material at the bottom of the image). A comparison between the middle and right images also shows a slight contraction of the polar vortex because of these waves. link https://ozonewatch.gsfc.nasa.gov/facts/vortex_NH.html And here is another good read https://www.sciencedirect.com/topics/earth-and-planetary-sciences/polar-vortex sample section from above link Wave-2/vortex splitting type The most dramatic major warmings involve a complete split in the polar vortex, followed by a rapid breakdown of one or both of the two cyclonic vortices that result from this split. The growth of the Aleutian High is accompanied by the development of a second anticyclone in the vicinity of the Greenwich Meridian at 0° E. An unusually symmetrical example of a ‘wave-2’ major warming occurred in northern winter 1984/85. Its evolution is illustrated in Figure 7. There are two developing anticyclones: the Aleutian High near 180° E and another (nonclimatological) anticyclone near 0° E. The polar vortex was split in the ‘pincer’ formed by these anticyclones, which then merged over the pole, as shown in Figure 8, bringing warm air over the polar cap. Subsequently, both of the cyclones weakened rapidly as they were stretched out around the strong anticyclone over the pole. Often, vortex splitting events are preceded by a ‘preconditioning’ of the vortex in which it is displaced from the pole and elongated. This preconditioning has a strong signature in the wave number one geopotential height field meaning that separating vortex displacement and vortex splitting events purely on the basis of the amplitudes of the wave number one and two geopotential height field can be difficult. Instead, alternative methods, which focus on examining the two- and three-dimensional structure of the potential vorticity fields have proved a useful complement to traditional methods in classifying and understanding SSWs in recent years.

The idea is it could interfere with the base state if it occurs too early. Just because you get a SSWE does not mean the outcome for cold and snow in our area is guaranteed. Many times a simple disruption and keeping the PV on our side of the pole is good enough. As @WxUSAF mentioned a SSWE later in the season is probably good for us. This year with a descending QBO that should help us with blocking. I read that currently wave 2 activity is/will taking punches to PV , but I believe we do not have significant wave 1 activity. There are some precursor patterns that show up and you can look to these to place stress on the PV. Lastly, I read that the set up for this winter does not favor an official SSWE happening. In that context I am happy with the way things are proceeding without a SSWE messing things up. I know Isotherm is releasing his winter outlook soon, I respect his work and I am sure he will focus on the strat and the NAO domain.

I came across an interesting read a few days ago that showed a very close correlation between October's SAI and the following winter's AO, which revealed a -_AO in the winters following robust October snowfall in the Northern Hemisphere and below 60 degrees North. This correlation came in the time period 07 to 11 the post mentioned. Problem is since then the correlation has been a erratic at best, and the ensuing winter's AO was not predominantly negative. The overall results were mixed. Whether this has to do with the recent sea ice losses, later starts to winters , I am not sure. That is why after 2011 the magic was lost to a degree. Judah did get a lot of press during the winters of 13-14 and 14-15 with the PV visits but by then folks were questioning the validity of the SAI.

Just checked out the Euro Northern Hemisphere look, really stunning . Thanks for the tip, I had no idea about the access there.

I believe Judah's second follow up post was directed at @psuhoffman as a disclaimer of sorts ..... Always good to say, not a forecast, not everywhere will be cold. Hey, at least we have snow cover that' s all I am after. Here is my disclaimer psu - I am a not a Judah supporter, this post was paid for by the Alliance of Snow Advance Index Members, all 3 of them.

Pretty crazy look forecasted around mid November and the implications for the strat.

Continued trends downward with the AO and trending up with the PNA

The MJO has gotten my interest as of late . Also of note, the lack of the MJO going into very high amplitude. Also, seeing the signs of more favorable phases for us here. There is a lot more to the MJO as well as certain phases aid in strat disruptions. I see today the SOI making a big move down as well 4 Nov 2019 1008.28 1010.80 -34.36 -4.51 -7.07 Keep this in mind as well

Many folks share this view. Some concerns are increasing the odds that the holiday period will be very warm, such as recent years, also that the cold air mass is wasted because snow climo itself is still too early and hostile. However, some areas of the country I have seen in the past do start early, with cold and snow, and remain so during the heart of winter. I hope this is not a head fake. I believe there are plenty of reasons to expect cold and snow in the NE this winter.

Like last winter I would keep an eye on the ENSO region 1.2 If region 1.2 were to warm significantly I believe it could overwhelm the pattern for us here in the East in a negative fashion, and lead to warmth and a poor storm track. There are many favorable elements that are pointing to cold and snow, but I prefer we remain in the SST profile that we have basically have maintained the last several months in Pac. If BAMMWX is bringing up the potential warming of ENSO 1.2 as a possible concern it gets my attention. This of course goes with the notion that most of us here know that region 1.2 is prone to wild short-term fluctuations.

Taken with a grain of salt , but nice to see the AO negative and staying negative. I think the Euro Ensemble index more likely to be correct. ( last image )

Great Lakes to cool off and snow in SE Canada. Very impressive forecast map. The question later in the month is whether there is a whole sale pattern change, or just a relaxation , even a version of an Indian summer if you may. I remember Joel Myers saying in the old days , 1970's and 1980's you can only pull the rubber band so much before it pulls back or snaps. In this case keeping a highly anomalous winter like pattern for an extended period of time makes you wonder the implications for the first 1/3 of the meteorological winter. Of course, there are things that argue after a brief to moderate relaxation we go back to what the base state may want to provide, which is an active storm track(s), and penetrations of cold air. this takes place as wavelengths continue to lengthen.

@showmethesnow I brought up the record +PMM a month or so ago. Rolling forward from Sept. to November and then December a very high +PMM gives a decent signal for a cold November in the East , and a even more robust cold signal for December. I even recall it has, in December, the ability to help in phasing and in introducing a more active and present STJ stream, through longer wavelengths, . Not saying it is going to work out, because about 90 % of mets are going with a warm December this year. I feel we can go normal with colder risks and stormier as well. BAMMWx so far is on a roll.

Nice seeing some pressure being applied on the PV to keep it from rapidly getting stronger. As HM stated, you simply can not go by the last days of October and early November, in regards to the PV strength, as a proxy to the implications for the ensuing winter. Also seems we are taking a different approach this late Fall with the location of the PV and the general behaviors in the HL. Some similarities later next week if we get a significant snow storm to our North, but feeling that does not gloom the winter coming up. Also, looking back at the summer in the Northern Plains and continuing even now with the placement of the coldest anomalies, well they seem to want to take shop on our side of the pole. Not seeing any red flags so far with the MJO. and nice seeing the + PNA kick up.

A most interesting set-up in terms of the warming origins.

Low of 31 degrees here this morning. Heavy frost almost like a covering of light snow.

Maybe the early November cold has legs.

This makes a lot of sense and goes along with some of the mets I follow. The talk from some of them, including HM here is that "if" the seasonal models are indeed getting the winter NAO signal from forecasting and anticipating a strong to very strong PV, well, if the vortex if weaker, or more prone to shifts and elongations then the seasonal call for a mostly + NAO during December through Feb. might be very wrong. Taken a step further would potentially equate to a very different sensible weather outcome for some folks. Please keep in mind HM is talking about the AO and I am inferring the association to the NAO domain and the relationship of a not so strong PV.

If the UKmet couldn't forecast the seasonal NAO last winter, even after doubling down in November, how the hell can this trash model even attempt a seasonal forecast and for 4 months in a row as well of a + NAO ? Wait, persistence is modeled into the physics. It does have company, but many models last Fall called for a -NAO average during the winter. I don't buy it yet.